Damper device for railway vehicle automatic couplings

ABSTRACT

A damper device for automatic couplings in railway vehicles has elastic and hydraulic parts, the hydraulic part being doubleacting and having two chambers which are interconnected through a variable flow restriction, for example a nozzle formed in part by a shaped axial pin, such that the damping force varies progressively in response to movement applied to the device.

United States Patent 1191 Brambilla et aL,

DAMPER DEVICE FOR RAILWAY VEHICLE AUTOMATIC COUPLINGS Inventors: GuidoBrambilla; Vittorio Fogliacco,

both of Turin, Italy RIV-SKF Olficine Di Viliar Perosa S.p.A., Turin,Italy Apr. 7, 1971 Assignee:

Filed:

App]. No.: 132,026

Foreign Application Priority Data May 4, 1970 Italy ..68534 A/7l) us.(:1. ..213/45, 213/43, 267/35 Int. Cl ..B6lg 9/08 Field of Search..213/8, 40 R, 40 D, 213/43, 45, 223; 267/64 R, 65 R, 35;

References Cited UNITED STATES PATENTS 5/196] Simmons ..2l3/43 1451 Apr.24, 1973 Primary Examiner-Drayt0n E. Hoffman Attorney-Sughrue, Rothwell,Mion, Zinn & Macpeak [57] ABSTRACT A damper device for automaticcouplings in railway vehicles has elastic and hydraulic parts, thehydraulic part being double-acting and having two chambers which areinterconnected through a variable flow restriction, for example a nozzleformed in part by a shaped axial pin, such that the damping force variesprogressively in response to movement applied to the device.

1 Claim, 4 Drawing Figures Patented April 24, 1973 I 2 Sheets-Sheet 2DAMPER DEVICE FOR RAILWAY VEHICLE AUTOMATIC COUPLINGS BACKGROUND OF THEINVENTION This invention relates to damper devices for automaticcouplings of railway vehicles.

As is known, the task ofdamper devices in railway vehicle coupling is toabsorb the energy of the impact between two vehicles upon couplingthereof and to return only a small part of this energy to the vehicles,thereby minimizing recoil.

Damper devices are known which are made up solely of metal springs or ofelastomeric material: such 7 resilient damper devices are able to absorbenergy but not to disperse it sufficiently.

Mixed dampers are known which have an elastic part and an hydraulic partwhich, whilst permitting better results, do not permit precise controlof the damping characteristics during impact between two vehicles.

An object of the present invention is to avoid the said disadvantages byproviding a damper device which operates efficiently upon impact withgood energy ab- SUMMARY OF THE INVENTION According to the inventionthere is provided a damper device for automatic couplings of railwayvehicles, comprising an elastic part, a double-acting hydraulic parthaving two chambers, and means interconnecting the two chambersincluding an element responsive to movement applied to the device tovary progressively the effective resistance to flow of hydraulic fluidbetween said two chambers.

BRIEF DESCRIPTION OF THE DRAWINGS Some practical embodiments of theinvention will now be described by way of non-limiting example, withreference to the accompanying drawings, in which:

FIG. 1 is a diagrammatic axial section of a damper device according toone embodiment of the invention;

FIG. 2 is a diagrammatic axial section of part of a damper deviceshowing a variant of the embodiment of FIG. 1;

Hg. 3 is a cross section taken along IIIIII of FIG. 2, and

FIG. 4 is a diagram illustrating the reaction characteristic of thedamper device as a function of the relative movement to which it issubjected.

DETAILED DESCRIPTION WITH REFERENCE TO THE DRAWINGS As illustrated inFIG. 1, the damper device according to the invention includes an elasticpart constituted by a stack of flat metal elements 1, in the form offlat plates, on to each of which is stuck a respective elasticallyyielding element 2, preferably of high hysteresis rubber. The elasticelements 2 are assembled in the device in a pre-compressed state. Theelastic elements 2 are each provided with co-operating projections andindentations 1a, 2a, on their opposite flat faces to allow interlockingof each element 2 with the adjacent elements of the stack, the metalelements 1 having suitable recesses to permit such interlocking.

The stack of elements I, 2 forming the elastic part of the damper deviceis interposed between a terminal plate 3 and a casing 4 situated atopposite ends of the stack and movable relatively to each other.

The damper device further includes an hydraulic part which is containedin the, casing 4. The hydraulic part comprises a stem 6 mounted forsealed sliding movement within a tubular appendage 5 of the casing 4 andbearing at one end, within the casing, a piston 7 which makes sealedsliding contact with the internal surface of a cylinder 8 housedcoaxially within the casing 4. An interior chamber A is defined withinthe cylinder 8 between the piston 7 and a sealing base 9.

The cylinder 8 is surrounded by an annular tank 10, which acts as areservoir for the hydraulic fluid (oil). The reservoir tank 10communicates with the chamber A of the cylinder 8 by means of at leasttwo sets of passages 11 13. The first passage 11 opens into the chamberA through a non-return valve 12, within the base 9, which is adapted toclose when the pressure in the chamber A exceeds that in the passage 11,while the other passage 13 opens into the chamber A through a non-returnvalve 14 within the base 9 which opens only when the pressure in thechamber A exceeds that in the passage 13 by at least a predeterminedamount, determined by the force of a spring acting on said valve.

The end of the stem 6 adjacent thepiston 7 is provided with an axialblind bore 15 which communicates with the chamber A of the cylinder 8through a calibrated nozzle 16. The nozzle 16 is partly defined by acentral pin 17, projecting axially from the base 9 of the cylinder andhaving a cross-section which varies along its length so as to vary theeffective nozzle aperture in dependence upon the positition of thepiston 7 within the cylinder 8. The blind bore 15 of the stem 6communicates with a rear chamber B within the cylinder 8, on the otherside of the piston 7 from the chamber A, by means of drillings 18.

The piston 7 is also provided with one or more axial passages 19(one'only of which is shown) normally closed by non-return valves 20which can open only during the approach of the piston 7 towards thecylinder base 9.

The operation of the damper device will now be described.

It will be supposed that some external action initiates an axialcompression of the device, the chamber A being full of oil.

chamber B, the valves 20 being open at this stage to permit such flow.

Because the stem 6 of the piston 7 enters the cylinder chamber B it isnot possible for all the oil expelled from the chamber A to pass intothe chamber B; part of this oil therefore flows out of the cylinder 8through the passages 13 controlled by the non-return valves 14 andenters the reservoir tank 10.

The resistance offered by the damper device to the applied compressionresults from the combined flowrestricting action of the valves 20 and 14and the throttling action of the nozzle 16, which throttling actionvaries as the piston 7 approaches the cylinder base 9 by virtue of thevarying cross section of the pin 17.

In the embodiment illustrated in FIG. 1 the damper device is adapted toachieve the damping of impacts such as occur upon coupling of tworailway vehicles and the pin 17 has a conical shape, tapering in crosssection away from the base 9, presupposing that the speed of the pistonis to decrease linearly and with a damping coefficient which isinversely proportional to the speed ofthe piston 7 in the cylinder 8.

The damper device may be arranged so as to provide a constant reactionduring impact by making the elastic part and the hydraulic part withcomplementary characteristics, as shown graphically in Fig. 4. FIG. 4shown, superimposed, the reaction characteristics of the elastic part(curve 25) and the hydraulic part (curve 26) of the device: the sum ofthe ordinates of the two curves 25 and 26 is constant over a range ofrelative movement of the piston 7 and cylinders 8, represented on theabscissa x. In the two curves 25 and 26 the ordinates y represent thevalues of the total reaction exerted by the respective parts of thedamper device for the maximum speed ofimpact.

The pin 17 could be shaped in different ways in order to obtaindifferent specific behavior characteristics from the damper device.

The return or recovery phase of movement of the damper device after animpact is brought about by the reaction exerted by the compressed stackof elastic elements 2. As the compression of the elements 2 is relievedthe piston 7 is drawn away from the cylinder base 9 and oil is able topass from chamber 8 to chamber A only through the drillings 18 and thenozzle 16, since the non-return valves 20 are closed. Consequently aconsiderable damping force is exerted in this phase, giving a low returnspeed for the piston 7.

Owing to the presence of the stem 6 within the chamber B the increase involume of the chamber A exceeds the reduction in volume of the chamber Band this discrepancy is made up by oil flowing into the chamber A,through the non-return valves 12, from the reservoir tank 10, so thatthe chamber A is always entirely full of oil.

In FIGS. 2 and 3 there is illustrated a variant of the damper device inwhich the conical pin 17 is replaced by a tubular element 21 securedcentrally to the base 9 of the cylinder 8. The tubular element 21 isprovided with radial vents 22 distributed in the wall of the element 21according to a pre-arranged pattern and adapted to allow flow of theoil, with a predetermined rotational ad'ustment of the rod 23 beingeffected from outside and he rod being lockable by means of a ring nut24 or equivalent means.

The inner rod 23 is in the shape of a cylinder with two diametricallyopposite longitudinal channels in its surface (FIG. 3). The solidportions of the rod 23 between the longitudinal channels can be arrangedto obstruct, at least partially, the vents 22 in the wall of the tubularelement 21 by adjusting the relative angular position of the rod 23within the tubular element 21. The damping regimen can therefore bevaried at will by adjusting from the outside the angular position of therod 23 within the tubular element 21.

The longitudinal distribution of the vents 22 in the wall of the tubularelement 21 allows of a progressive damping of the piston travel,analogously to the varying cross section of the pin 17 in the embodimentof FIG. 1, while the circumferential distribution of the vents 22 allowsof a greater or lesser range of adjustment of the overall dampingcharacteristics of the device by means of the rod 23.

It will be appreciated that details of construction of specificembodiments of the invention may be varied widely from those describedand illustrated, without nevertheless departing from the scope of thisinvention.

What is claimed is:

l. A damper device for an automatic coupling of a railway vehiclecomprising a cylinder for containing hydraulic liquid, a piston slidablymounted in said cylinder and dividing said cylinder into a first chamberand a second chamber, said piston having a passage therethroughinterconnecting said first and second chambers, a flow regulatingelement fixed in said first chamber and extending into said passage,said piston having a stem extending axially outwardly of said cylinder,a terminal force receiving plate secured to the end of said stem andresilient means disposed intermediate said terminal force receivingplate and said cylinder, and means for compensating changes in thecombined volume of said first and second chambers upon movement of thepiston and stem within said cylinder, said compensating means comprisingwall means defining an annular auxiliary chamber surrounding saidcylinder for containing hydraulic fluid and a gas, first and secondconduit means extending between said auxiliary chamber and said firstchamber, first valve means associated with said first conduit forpermitting the unrestricted flow of hydraulic fluid from said auxiliarychamber to said first chamber but totally preventing the flow from saidfirst chamber to said auxiliary chamber and a second valve meansassociated with said second conduit having calibrated spring means whichpermits restricted flow of hydraulic fluid from said first chamber tosaid auxiliary chamber but prevents flow from said auxiliary chamber tosaid first chamber.

1. A damper device for an automatic coupling Of a railway vehiclecomprising a cylinder for containing hydraulic liquid, a piston slidablymounted in said cylinder and dividing said cylinder into a first chamberand a second chamber, said piston having a passage therethroughinterconnecting said first and second chambers, a flow regulatingelement fixed in said first chamber and extending into said passage,said piston having a stem extending axially outwardly of said cylinder,a terminal force receiving plate secured to the end of said stem andresilient means disposed intermediate said terminal force receivingplate and said cylinder, and means for compensating changes in thecombined volume of said first and second chambers upon movement of thepiston and stem within said cylinder, said compensating means comprisingwall means defining an annular auxiliary chamber surrounding saidcylinder for containing hydraulic fluid and a gas, first and secondconduit means extending between said auxiliary chamber and said firstchamber, first valve means associated with said first conduit forpermitting the unrestricted flow of hydraulic fluid from said auxiliarychamber to said first chamber but totally preventing the flow from saidfirst chamber to said auxiliary chamber and a second valve meansassociated with said second conduit having calibrated spring means whichpermits restricted flow of hydraulic fluid from said first chamber tosaid auxiliary chamber but prevents flow from said auxiliary chamber tosaid first chamber.